He also said that such a hefty fine could have a serious impact on already tricky negotiations over a transatlantic free trade agreement (TTIP)."This commercial partnership can only be established if it's based on reciprocity," Fabius told France 2.

If the US levied the penalty on one of Europe's biggest bank, as reported by the Wall Street Journal last Thursday, it would be a "unilateral and unjust" decision, the minister said.

The US Justice Department and BNP, which is France's biggest lender, declined to comment on the report.

BNP Paribas is alleged to have violated US sanctions in place against Sudan, Iran and Syria between 2002 and 2009. The bank has been negotiating with US authorities for months on a settlement for a criminal probe relating to those charges.

BNP is one of several banks being probed. The alleged fine would be the biggest ever paid for similar offenses by any big bank.

BNP shares
plunged last Friday, after the Journal report was published, dragging down the bluechip CAC40.

Some analysts fear that a hefty fine could erode the bank's capital, as it has only made a $1.1-billion provision for this case. Press reports say that US authorities may also consider temporarily restricting the bank's ability to process dollar transactions.